剪切振动下湿颗粒的力学谱  

Wet granular matter mechanical spectroscopy under low-frequency shear

作　　者：唐瀚玉 王娜 吴学邦 刘长松 Tang Han-Yu;Wang Na;Wu Xue-Bang;Liu Chang-Song(Key Laboratory of Materials Physics,Institute of Solid State Physics,Chinese Academy of Sciences,Hefei 230031,Chino)

机构地区：[1]中国科学院固体物理研究所材料物理重点实验室,合肥230031

出　　处：《物理学报》2018年第20期427-432,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11374298;11174283);中国科学院青年创新促进会(批准号:2015384)资助的课题~~

摘　　要：在恒温25℃剪切振动条件下,测量不同水分含量的NaCl湿颗粒体系的力学谱(能量耗散tanφ和剪切模量G).研究发现,随着剪切振幅增大,NaCl湿颗粒体系的剪切模量G和能量耗散tanφ都表现出类似于干颗粒体系的阻塞(Jamming)转变行为.随着体系中水含量的增大,湿颗粒体系的剪切模量G和能量耗散tanφ在质量分数约等于11%的临界水浓度下均出现一个峰值,且峰位与应变振幅无关,表明此时颗粒之间主要的作用力发生了变化.Dry granular materials consist of a collection of macroscopic discrete particles interacting solely via contact forces.By changing the external conditions, the granular packing displays rich phenomena ranging from fluid-like properties to jamming glassy behavior and to aging observed when these grains are trapped in a frozen state. Once the grains contact liquid, the force between the liquid and grains has an influence on the mechanical properties of the wet granular materials, and some mechanical behaviors are quite different from those of the dry granular materials. However, the underlying mechanism of the complex dynamics of granular assemblies is still not completely understood.In this paper, mechanical spectroscopy（the shear modular G and the related energy dissipation tan φ） of NaCl wet granular system is investigated with different liquid content（weight fraction） under the constant temperature 25 ℃and air humidity by a modified low-frequency inverted torsion pendulum. The NaCl wet granular system also displays jamming behavior when subjected to an external vibration with increasing intensity, which is quiet similar to dry granular matter. With the increase of water content, all the spectra of tanφ and modular G show a peak at the water content about 11%（critical water content）. At the same time, the applied shear force has little influence on the positions of these peaks. All of these behaviors illustrate that the main interaction forces among granular matters in the system are changed at the moment.

关 键 词：湿颗粒体系 力学谱 液桥力 

分 类 号：O347.7[理学—固体力学]